Anemic looking Yolks?

My chickens are freerange and get fed a commercial layer feed, in addition to treats of fruit/dry catfood, etc. Last year their yolks were a GORGEOUS dark orange (when they weren't freeranging but were given lots of treats). This year they are a pale yellow (like store bought eggs). What gives? The chickens are coming out of a moult and only a couple are laying- could this be the reason why? All appear to be healthy and happy. I know I'm doing something wrong but can't think of what it is.

Got a bag of BOSS today to up the protein in their diet a bit if that's it. I will be worming them tonight (cuz I did the dogs and cats a couple days ago and they had a few dead ones in their stool today) so everyone is getting wormed.

I have ordered some dried kelp to mix up with their food.

Is there anything else I should do- I'm looking at the pale yolk color as an indicator that something is not right with them.

The greens aren't as good- we are in the process of turning a bramble laden field into a lawn but there is grass. What would be some good greens to grow for the chickens to make the eggs the nice deep orange that I miss?